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-rw-r--r--boost/parameter/aux_/is_maybe.hpp58
1 files changed, 42 insertions, 16 deletions
diff --git a/boost/parameter/aux_/is_maybe.hpp b/boost/parameter/aux_/is_maybe.hpp
index b875852847..0069eddc14 100644
--- a/boost/parameter/aux_/is_maybe.hpp
+++ b/boost/parameter/aux_/is_maybe.hpp
@@ -1,26 +1,52 @@
-// Copyright Daniel Wallin, David Abrahams 2010. Use, modification and
-// distribution is subject to the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
+// Copyright Daniel Wallin, David Abrahams 2010.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_PARAMETER_IS_MAYBE_050329_HPP
#define BOOST_PARAMETER_IS_MAYBE_050329_HPP
-#include <boost/type_traits/is_base_and_derived.hpp>
+namespace boost { namespace parameter { namespace aux {
-namespace boost {
-namespace parameter {
-namespace aux {
+ struct maybe_base
+ {
+ };
+}}} // namespace boost::parameter::aux
-struct maybe_base {};
+#if defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <type_traits>
-template <class T>
-struct is_maybe
- : is_base_and_derived<maybe_base, T>
-{};
+namespace boost { namespace parameter { namespace aux {
-} // namespace aux
-} // namespace parameter
-} // namespace boost
+ template <typename T>
+ using is_maybe = ::std::is_base_of<
+ ::boost::parameter::aux::maybe_base
+ , typename ::std::remove_const<T>::type
+ >;
+}}} // namespace boost::parameter::aux
+
+#else // !defined(BOOST_PARAMETER_CAN_USE_MP11)
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_base_of.hpp>
+#include <boost/type_traits/remove_const.hpp>
+
+namespace boost { namespace parameter { namespace aux {
+
+ template <typename T>
+ struct is_maybe
+ : ::boost::mpl::if_<
+ ::boost::is_base_of<
+ ::boost::parameter::aux::maybe_base
+ , typename ::boost::remove_const<T>::type
+ >
+ , ::boost::mpl::true_
+ , ::boost::mpl::false_
+ >::type
+ {
+ };
+}}} // namespace boost::parameter::aux
+
+#endif // BOOST_PARAMETER_CAN_USE_MP11
+#endif // include guard
-#endif // BOOST_PARAMETER_IS_MAYBE_050329_HPP